1、 PDF外文：http:/ 附录 附录一：外文原文 Temperature Control Using a Microcontroller: An Interdisciplinary Undergraduate Engineering Design Project James S. McDonald Department of Engineering Science Trinity University San Antonio, TX 78212 Abstract This paper describes an interdisciplinary desig
2、n project which was done under the authors supervision by a group of four senior students in the Department of Engineering Science at Trinity University. The objective of the project was to develop a temperature control system for an air-filled chamber. The system was to allow entry of a desired cha
3、mber temperature in a prescribed range and to exhibit overshoot and steady-state temperature error of less than 1 degree Kelvin in the actual chamber temperature step response. The details of the design developed by this group of students, based on a Motorola MC68HC05 family microcontroller, are des
4、cribed. The pedagogical value of the problem is also discussed through a description of some of the key steps in the design process. It is shown that the solution requires broad knowledge drawn from several engineering disciplines including electrical, mechanical, and control systems engineering. 1
5、Introduction The design project which is the subject of this paper originated from a real-world application. A prototype of a microscope slide dryer had been developed around an OmegaTM model CN-390 temperature controller, and the objective was to develop a custom temperature control system to repla
6、ce the Omega system. The motivation was that a custom controller targeted specifically for the application should be able to achieve the same functionality at a much lower cost, as the Omega system is unnecessarily versatile and equipped to handle a wide variety of applications. The mechanica
7、l layout of the slide dryer prototype is shown in Figure 1. The main element of the dryer is a large, insulated, air-filled chamber in which microscope slides, each with a tissue sample encased in paraffin, can be set on caddies. In order that the paraffin maintain the proper consistency, the temper
8、ature in the slide chamber must be maintained at a desired (constant) temperature. A second chamber (the electronics enclosure) houses a resistive heater and the temperature controller, and a fan mounted on the end of the dryer blows air across the heater, carrying heat into the slide chamber. This
9、design project was carried out during academic year 199697 by four students under the authors supervision as a Senior Design project in the Department of Engineering Science at Trinity University. The purpose of this paper is to describe the problem and the students solution in some detail, an
10、d to discuss some of the pedagogical opportunities offered by an interdisciplinary design project of this type. The students own report was presented at the 1997 National Conference on Undergraduate Research 1. Section 2 gives a more detailed statement of the problem, including performance specifica
11、tions, and Section 3 describes the students design. Section 4 makes up the bulk of the paper, and discusses in some detail several aspects of the design process which offer unique pedagogical opportunities. Finally, Section 5 offers some conclusions. 2 Problem Statement The basic idea o
12、f the project is to replace the relevant parts of the functionality of an Omega CN-390 temperature controller using a custom-designed system. The application dictates that temperature settings are usually kept constant for long periods of time, but its nonetheless important that step changes be trac
13、ked in a reasonable manner. Thus the main requirements boil down toallowing a chamber temperature set-point to be entered,displaying both set-point and actual temperatures, andtracking step changes in set-point temperature with acceptable rise time, steady-state error, and overshoot. Although
14、not explicitly a part of the specifications in Table 1, it was clear that the customer desired digital displays of set-point and actual temperatures, and that set-point temperature entry should be digital as well (as opposed to, say, through a potentiometer setting). 3 System Design The requirements for digital temperature displays and setpoint entry alone are enough to dictate that a microcontrollerbased design is likely the most appropriate. Figure 2 shows a block diagram of the students design.
